Engineering Blog

Since 2018: Watershed Studies

posted September 8, 2022

The City of Madison Engineering Division is focusing on a number of projects to show what the City and Engineering has done ‘Since 2018’ when a flood devastated our community on Aug. 20, 2018. In this blog post, we spoke with City of Madison Engineering Division Stormwater Engineer Caroline Burger about the Watershed Studies and how they will impact the community with providing solutions to flooding.

What was the problem with flooding as a whole?

“Excess flooding can cause property damage and impacts to public health and life. In August 2018, the west and southwest sides of the City experienced unprecedented rainfall. The City’s stormwater system is not designed to handle that much water. As a result, homes and businesses flooding and one person lost their life.”

What did we do to fix it?

“Shortly following the August 2018 event, Engineering began a comprehensive watershed study program to try to address flooding. The City has 22 watersheds. Each watershed is complex and unique. Each watershed is being studied to understand what causes the flooding. Then, once that is understood, solutions can be developed to reduce flooding. Of the 22 watersheds, four watershed studies are complete and 14 are progress. The remaining four will start their studies in 2023 or 2024. In addition to the watershed study program, the City’s stormwater ordinance was revised to include stricter flood control standards.”

Why was there a problem/why did we fix it?

“The cause of flooding is complex and situation dependent. In some areas, the stormwater infrastructure is very old and was designed using standards that are now outdated. In other areas, structures were built too low. In other areas, the ground is very flat, or even a little depressed, so it is hard to drain the areas. The increased rainfall amounts and intensity from climate change only makes the flooding in these areas worse. The proposed solutions developed from the watershed studies will reduce flood risk for as many areas as possible.”

How much was the project?

“Each watershed study costs approximately $250,000 and two years to complete. The total watershed study program is about $7 million over seven years. Each watershed study takes significant staff time to manage the studies so that all watersheds in the City are studied consistently. For most watershed studies, the complex computer modeling is outsourced to a consultant due to staff capacity limitations. Engineering has added additional public input to most of the watershed studies to try to obtain as much public feedback as possible.”

How long will it take us to fix it?

“The target is to try to complete all the watershed studies by 2026. The projects stemming from the watershed studies will be compiled and then programmed in the City’s Capital Improvement Program (CIP) budget as funding allows. At the time of this blog, from the first seven studies, there are approximately 65 proposed solutions totaling $250 million. It is expected the remaining studies will generate similar magnitudes of projects. Due to budget limitations, it will take decades to implement the flood reduction solutions citywide.”

How much of an impact does this project have from a bigger picture perspective? Why is this important?

“The watershed studies are providing information on the causes of flooding for each watershed. We will soon understand the causes across the City. Once we know the cause, we can then craft solutions to reduce the flooding.

Engineering staff understands reducing flooding is going to be a very expensive endeavor (hundreds of millions of dollars). We want to spend the money we have on the projects that will make the most impact and will not cause adverse impacts. The stormwater infrastructure within each watershed is interconnected – something we do in one place affects another place. Therefore we wanted to take a holistic look at the stormwater system and each watershed. This holistic look creates the foundation of our stormwater program. With this new knowledge, we can make the best decisions for our public stormwater system. The watershed study results are also being used to inform stormwater for developments across the City. Developments are provided minimum elevations for structures so that structures will be set above the flood risk elevations. This means long term, very few, if any structures will be too low.”